Hope this helps some people.Just a new trick that i learned actually just last night

WARNING! THIS TUTORIAL ONLY WORKS WITH PHOTOSHOP CS3!!! Please do not ask me about making it for CS2 because CS2 doesn't have the same ability. But if you think it does, please go ahead and try it. I might be wrong

Thanks for this! I've used this on Photoshop CS4 with nice results, but you can also get the same effect in CS2 at least by, instead of using the Black and White Green Filter, using the Green channel from the Channels window. Choose the Green channel, copy merged, turn RGB back on then paste into a new layer. You'll get the same greyscale layer as if you had used Black and White.